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  Partner: UNT Libraries
 Department: Department of Chemistry
 Collection: UNT Theses and Dissertations
Synthesis, Stability, and Reactions of Dichloroketene

Synthesis, Stability, and Reactions of Dichloroketene

Date: June 1965
Creator: Liddel, Harold Glenn
Description: The primary objective of this work was to prepare dichloroketene.
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Separation of Transition Metal Ions by HPLC, Using UV-VIS Detection

Separation of Transition Metal Ions by HPLC, Using UV-VIS Detection

Date: August 1987
Creator: Lien, Wan-Fu
Description: HPLC has been used and can quickly determine several ions simultaneously. The method of determination described for transition metals [Cr(III), Fe(III), Ni(II), Co(II), Cu(II), Zn(II), Cd(II), Mn(II)] and [Ca(II), Pb(II)] using HPLC with UV-VIS detection is better than the PAR complexation method commonly used. The effects of both eluent pH and detector wavelength were investigated. Results from using different pHs and wavelengths, optional analytical conditions for the separation of [Ni(II), Co(II), Cu(II)], [Cr(III), Fe(III), Ca(II), Ni(II), Cu(II)], and [Ca(II), Zn(II), Pb(II)] in one injection, respectively, are described. The influence of adding different concentrations of Na_2EDTA solvent to the sample is shown. Detection limits, linear range, and the comparisons between this study and a post-column PAR method are given.
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Studies on the Porphyrin and Phthalocyanine Modified on Sno2 Photoelectrochemical Cells

Studies on the Porphyrin and Phthalocyanine Modified on Sno2 Photoelectrochemical Cells

Date: December 2013
Creator: Lin, Chunyu
Description: The world is facing a tough challenge regarding fulfilling human energy needs. Scientists are motivated to find alternative ways to the fossil fuel at a lower cost with little or no environmental pollution. Among the available renewable resources, the solar energy is an alternative energy to fossil fuel. Scientists are engaged in mimicking the photosynthesis to create the new energy devices such as dye sensitized solar cells. The fundamental theory and properties of the dye sensitized solar cells is given in the first chapter. In this research, the application of the different methods for surface alteration of SnO2 with water soluble porphyrins and phthalocyanine is studied. Using optical absorbance and steady state fluorescence studies, the formation of porphyrins and phthalocyanine discuss on the SnO2 surface is shown. Moreover, the different results of photoelectrochemical cells are show on chapter 2 to understand the porphyrin and phthalocyanine modified on SnO2 as electron injector. In summary, the application porphyrin and phthalocyanine of dimers as a broad band capturing photosensitized dye is discussed.
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Thermal Decomposition of Alkyllithium Compounds in the Pure State

Thermal Decomposition of Alkyllithium Compounds in the Pure State

Date: January 1965
Creator: Lin, Jacob Wen-pin
Description: This thesis is concerned with the thermal decomposition of a series of alkyllithium compounds in the pure state in an attempt to determine the relative stability of alkyllithium compounds and to examine the mechanism of the elimination reaction.
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Electrochemical Quartz Crystal Microbalance Study Of Bismuth Underpotential Deposition On Ruthenium And On Electrochemically Formed Ruthenium Oxide

Electrochemical Quartz Crystal Microbalance Study Of Bismuth Underpotential Deposition On Ruthenium And On Electrochemically Formed Ruthenium Oxide

Date: December 2011
Creator: Lin, Po-Fu
Description: Kinetics and thermodynamics of bismuth (Bi) underpotential deposition (UPD) on ruthenium (Ru) and on electrochemically formed Ru oxide are studied using electrochemical quartz crystal microbalance technique. The Bi UPD and Bi bulk deposition are observed both on Ru and on electrochemically formed Ru oxide electrodes. The anodic peak potential of Bi UPD shifts slightly to positive potential as the scan rate increases. The peak current ratio (IAnode/ICathode) of Bi UPD and Bi bulk increases as the scan rate increases. Bi monolayer coverage calculated from mass (MLMass) and from charge (MLCharge) with scan rates dependent are compared both in Bi UPD region and in Bi bulk region. Stability and oxidation time effects are also investigated. Bi UPD on Ru and on electrochemically formed Ru oxide are quasi-reversible, scan rate independent, oxidation time dependent, and have higher plating efficiency on Ru. However, Bi bulk deposition on Ru and on electrochemically formed Ru oxide are quasi-reversible, scan rate dependent, oxidation time independent, and have higher plating efficiency on electrochemically formed Ru oxide. Both Bi UPD adatoms and Bi bulk are unstable in 0.5M H2SO4.
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Inhibitors of Dihydrofolate Reductase, 8-Oxapteridines

Inhibitors of Dihydrofolate Reductase, 8-Oxapteridines

Date: December 1974
Creator: Lin, Shwu-Ching H.
Description: The biological activities of some homeosterically related analogs of dihydrofolic acid have been examined involving pyrimido[4,5-b][l,4]oxazine (8-oxapteridine) derivatives. It is anticipated that these compounds might interfere with the essential intermediary metabolic functions of the vitamin and thus serve as potential chemotherapeutic agents. Preliminary toxicity studies in microbial assay systems were disappointing; however, inhibitory effects were demonstrated in cell free enzyme systems. A comparison of the structure/activity relationships was determined using two folic acid coenzyme systems, dihydrofolate reductase and thymidylate synthetase. The 2-amino-4-hydroxy-6-(substituted)-8-oxapteridines were generally more effective inhibitors than the corresponding 2,4-diamino analogs. The relative biological activity of a series of 2-amino-4-hydroxy-6-ω-phenylalkyl derivatives were examined, and the most active derivative was the 6-phenylethyl analog which appears to function as a mixed-type inhibitor involving partially competitive and partially non-competitive inhibition.
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Interactions of Clean and Sulfur-modified Reactive Metal Surfaces with Aqueous Vapor and Liquid Environments : A Combined Ultra-high Vacuum/electrochemistry Study

Interactions of Clean and Sulfur-modified Reactive Metal Surfaces with Aqueous Vapor and Liquid Environments : A Combined Ultra-high Vacuum/electrochemistry Study

Date: May 1998
Creator: Lin, Tien-Chih, 1966-
Description: The focus of this research is to explore the molecular-level interactions between reactive metal surfaces and aqueous environments by combined ultra-high vacuum/electrochemistry (UHV-EC) methodology. The objectives of this work are to understand (1) the effects of sulfate ions on the passivity of metal oxide/hydroxide surface layer, (2) the effects of sulfur-modification on the evolution of metal oxide/hydroxide surface layer, and (3) the effects of sulfur adsorbate on cation adsorption at metal surfaces.
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Intermediates for Paracyclophane Synthesis

Intermediates for Paracyclophane Synthesis

Date: August 1962
Creator: Lin, Ying-tsung
Description: It is proposed in this thesis that the imperfect systems of Cram and of Schubert be combined with some modifications.
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High Temperature Enthalpies of the Lead Halides: Enthalpies and Entropies of Fusion

High Temperature Enthalpies of the Lead Halides: Enthalpies and Entropies of Fusion

Date: June 1970
Creator: Linsey, Clarence W.
Description: The objectives of this investigation were: 1. To establish calorimetrically the transition temperature for the orthorhombic to cubic transition exhibited by PbF₂ and to determine the enthalpy of this transition. 2. To determine if the solid-solid phase transitions claimed in the literature for PbCl₂, PbF₂, PbBr₂, and PbI₂ were of thermodynamic importance, and if so, to determine the enthalpies of transition. 3. To determine if the discontinuous thermal expansions reported by Hsu for the lead halides were of thermodynamic importance. 4. To obtain reliable heat content data for the lead halides in both the solid and liquid states.
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Transition Metal Mediated C-o Bond Cleavage: From Co2 Activation to Lignin Degradation

Transition Metal Mediated C-o Bond Cleavage: From Co2 Activation to Lignin Degradation

Date: August 2013
Creator: Liu, Cong
Description: CO2 activation and conversion mediated by transition metal (TM) catalysts were investigated. Homogeneous catalysis of the reverse water gas shift reaction CO2+H2→H2O+CO was studied as a means to reduce CO2. β-diketiminato metal models L'MI ( L' =C3N2H5-; M = first-row TMs) were considered as potential catalysts. The thermodynamics of prototypical reaction pathways were simulated using B3LYP/aug-cc-pVTZ. Results show that middle series metal complexes result in more thermodynamically favorable properties; therefore, more detailed thermodynamic and kinetic studies were carried out for Mn, Fe, and Co complexes. On the other hand, heterogeneous catalysis of the reduction of CO2 to CO was carried out on Fe, Co, Ni, and Cu surfaces, using the PBE functional. Reaction barriers were calculated using the climbing image nudged elastic band method. Late 3d and 4d transition metal ion (Fe, Co, Ni, Cu, Ru, Rh, Pd, and Ag) mediated activation of dimethyl ether was studied to investigate the intrinsic catalytic properties of metals for C-O bond cleavage. A set of density functional theory (DFT) methods (BLYP, B3LYP, M06, M06-L, B97-1, B97-D, TPSS, and PBE) with aug-cc-pVTZ basis sets was calibrated with CCSD(T)/CBS calculations on reaction energies and barriers.
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Passivation effects of surface iodine layer on tantalum for the electroless copper deposition.

Passivation effects of surface iodine layer on tantalum for the electroless copper deposition.

Access: Use of this item is restricted to the UNT Community.
Date: May 2004
Creator: Liu, Jian
Description: The ability to passivate metallic surfaces under non-UHV conditions is not only of fundamental interests, but also of growing practical importance in catalysis and microelectronics. In this work, the passivation effect of a surface iodine layer on air-exposed Ta for the copper electroless deposition was investigated by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). Although the passivation effect was seriously weakened by the prolonged air exposure, iodine passivates the Ta substrate under brief air exposure conditions so that enhanced copper wetting and adhesion are observed on I-passivated Ta relative to the untreated surface.
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Substitution chemistry of the cobalt complexes RCCo3(CO)9 (R = H, CHO) with the diphosphine ligand: 4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione (bpcd). Syntheses, X-ray structures and reactivity.

Substitution chemistry of the cobalt complexes RCCo3(CO)9 (R = H, CHO) with the diphosphine ligand: 4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione (bpcd). Syntheses, X-ray structures and reactivity.

Date: December 2001
Creator: Liu, Jie
Description: The reaction between the tetrahedrane cluster RCCo3(CO)9{R = CHO (1), H (3)} and the redox-active diphosphine ligand 4,5-bis(diphenylphosphino)-4-cyclopenten-1,3- dione (bpcd) leads to the replacement of two CO groups and formation of RCCo3(CO)7(bpcd) {R = CHO (2), H (4)}. Clusters 2 and 4 are thermally unstable and readily transform into the new P-C bond cleavage cluster 5. All three clusters 2, 4, and 5 have been isolated and fully characterized in solution by IR and 31P NMR spectroscopy. VT 31P NMR data indicate that the bpcd ligand in RCCo3(CO)7(bpcd) is fluxional at 187 K in THF. Clusters 2, 4, and 5 have been structurally characterized by X-ray diffraction analyses.
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I. On the Mechanism of Acid Promoted Rearrangement of PCU-Derived Pinacols II. Synthesis of a Trimethyltrishomocubyl Helical Tubuland Diol

I. On the Mechanism of Acid Promoted Rearrangement of PCU-Derived Pinacols II. Synthesis of a Trimethyltrishomocubyl Helical Tubuland Diol

Date: May 1995
Creator: Liu, Zenghui
Description: I. Reductive dimerization of pentacyclo[5.4.0.0.^2,6.0^3,10.0^5'9]undecane-8-one-(PCU-8-one, 53) affords a mixture of meso and d,l pinacols (55a and 55b respectively). Acid promoted rearrangement of 55a and 55b conceivably can proceed with migration of C(7)-C(8) and/or C(8)-C(9) to form the corresponding pinacolone(s). In our hands, acid promoted rearrangement of 55a and 55b each proceeds with exclusive migration of C(7)- C(8) bond, thereby affording 58a and 59a respectively. Mechanistic features of this rearrangement are discussed. II. 4,7,1 l-trimethylpentacyclo[6.3.0.0.^2,6.0^3,l0.0^5,9]undecane-exo-4,exo-7-diol (23a) was successfully synthesized. This diol crystallizes in a helical tubuland lattice although its molecular structure does not possess C2 rotational symmetry.
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The Hydrolysis of α-(Benzenesulfonyl)-Acetophenone

The Hydrolysis of α-(Benzenesulfonyl)-Acetophenone

Date: 1950
Creator: Looney, Jesse M.
Description: In view of the unexpected behavior of α-(benzenesulfonyl)-acetophenone toward hydrolysis and because of the possible physiological importance of its derivatives it was deemed of interest to make a further study of the hydrolysis of this compound. It was decided to study both the acid and basic hydrolysis of this compound. The problem consisted of finding a satisfactory means of analyzing the hydrolysis products, and carrying out the hydrolysis under the different conditions.
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Sodium Ion Self-Diffusion in Molten Mixtures

Sodium Ion Self-Diffusion in Molten Mixtures

Date: August 1963
Creator: Lu, Chi Chang
Description: This work is an extension of Yin's work studying the diffusion of Na ion in the PbCl2-NaCl system, but at more dilute compositions of NaCl.
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Thermophysical and Mechanical Properties of Polymer Liquid Crystals and Their Blends

Thermophysical and Mechanical Properties of Polymer Liquid Crystals and Their Blends

Date: May 1994
Creator: López, Betty Lucy
Description: Tensile properties, namely the elastic modulus, tensile strength, percent of elongation at yield and at the break were determined for the pure components and blends. The results are connected to the respective phase diagrams and demonstrate that blending makes property manipulation possible. Blends for which the mechanical properties are better than those of pure EPs can be obtained.
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Pyridinium Derivatives of 9,10-Endo-o-Phenylene-9,10-Dihydro-1,4-Anthraquinone

Pyridinium Derivatives of 9,10-Endo-o-Phenylene-9,10-Dihydro-1,4-Anthraquinone

Date: 1956
Creator: Maglaughlin, Edward Phillip
Description: The compounds reported here were prepared for the purpose of determining the effects of active groups on the pyridine ring, and to determine the effects of substituted methyl groups on the nucleus. These compounds are to be tested for tuberculostatic activity.
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The One Electron Basis Set:  Challenges in Wavefunction and Electron Density Calculations

The One Electron Basis Set: Challenges in Wavefunction and Electron Density Calculations

Access: Use of this item is restricted to the UNT Community.
Date: May 2016
Creator: Mahler, Andrew
Description: In the exploration of chemical systems through quantum mechanics, accurate treatment of the electron wavefunction, and the related electron density, is fundamental to extracting information concerning properties of a system. This work examines challenges in achieving accurate chemical information through manipulation of the one-electron basis set.
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Preparation of Pyridinium Derivatives of 2,3-Dichloro-5(8?)-Nitro-1,4-Naphthoquinone

Preparation of Pyridinium Derivatives of 2,3-Dichloro-5(8?)-Nitro-1,4-Naphthoquinone

Date: 1955
Creator: Mahon, Frank
Description: This paper describes the preparation of pyridine derivatives of 2,3-dichloro-5(8?)-nitro-1,4-naphthoquinone. A method for the nitration of 2,3-dichloro-1,4-naphthoquinone is also described. Certain 4-n-alkyl, 3,4-dialkyl, and 4-cycloalkyl pyridine derivatives are caused to undergo condensation reactions with the nitrated naphthoquinone, giving rise to a series of compounds of the preceding type (X). All of the compounds prepared will be tested for anti-tubercular activity by Parke-Davis and Company.
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An Approach Towards the Total Synthesis of Clonostachydiol

An Approach Towards the Total Synthesis of Clonostachydiol

Date: August 1995
Creator: Maiti, Tushar B. (Tushar Baran)
Description: The syntheses of the unsymmetrical 14-membered bismacrolides have been reviewed. A total synthesis of clonostachydiol, the latest to join this family, has been attempted using trimethylsilyl acetylene as the builiding block and palladium catalyzed reactions for the formation of key bonds. The alkyne groups were introduced by Stille coupling of trimethylstannylethynyltrimethylsilane with an acid chloride for one fragment and by addition of lithiotrimethylsilyl acetylene to an aldehyde for the other. Lactic acid derivatives were chosen as starting materials for both fragments, thus introducing two of the chiral centers. The remaining stereocenters were introduced using stereoselective reductions of ketones.
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Free Radical Induced Oxidation, Reduction and Metallization of NiSi and Ni(Pt)Si Surfaces

Free Radical Induced Oxidation, Reduction and Metallization of NiSi and Ni(Pt)Si Surfaces

Date: August 2010
Creator: Manandhar, Sudha
Description: NiSi and Ni(Pt)Si, and of the effects of dissociated ammonia on oxide reduction was carried out under controlled ultrahigh vacuum (UHV) conditions. X-ray photoelectron spectroscopy (XPS) has been used to characterize the evolution of surface composition. Vicinal surfaces on NiSi and Ni(Pt)Si were formed in UHV by a combination of Ar+ sputtering and thermal annealing. Oxidation of these surfaces in the presence of either O+O2 or pure O2 at room temperature results in the initial formation of a SiO2 layer ~ 7 Å thick. Subsequent exposure to O2 yields no further oxidation. Continued exposure to O+O2, however, results in rapid silicon consumption and, at higher exposures, the kinetically-driven oxidation of the transition metal(s), with oxides >35Ǻ thick formed on all samples, without passivation. The addition of Pt retards but does not eliminate oxide growth or Ni oxidation. At higher exposures, in Ni(Pt)Si surface the kinetically-limited oxidation of Pt results in Pt silicate formation. Substrate dopant type has almost no effect on oxidation rate. Reduction of the silicon oxide/metal silicate is carried out by reacting with dissociated NH3 at room temperature. The reduction from dissociated ammonia (NHx+H) on silicon oxide/ metal silicate layer shows selective reduction of the metal oxide/silicate layer, ...
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Effects of Using Logic and Spatial Cybergames to Improve Student Success Rates in Lower-Division Chemistry Courses

Effects of Using Logic and Spatial Cybergames to Improve Student Success Rates in Lower-Division Chemistry Courses

Date: May 2011
Creator: Manrique, Carissa Janice
Description: A study was conducted to investigate the relationships between cybergaming treatment groups and the control group (N = 99: ncontrol = 8; nlogic = 29; nspatial = 30; ncombination = 32) with success in the organic chemistry I course as measured by achievement over a 10-week period. The treatment groups included logic training, spatial training, and combination logic-spatial training. Students' ability was measured by pre/post exams using the Group Assessment of Logical Thinking (GALT) to measure logic ability, Purdue Visualizations of Rotations (ROT) test to measure spatial skills, and the General-Organic-Biochemistry (GOB) Exam to measure content attainment. Finally, students' responses about participation in this experience were evaluated using open- and closed-ended questions on a self-developed survey. A second study was conducted to evaluate the relationship between the cybergaming treatment and control groups (N = 88: nexperimental = 27; ncontrol = 61) with success in the general chemistry I course as measured by achievement and final course averages and grades. The cybergaming treatment group underwent intensive combination logic-spatial training for 10 weeks. Students' progress was measured using three pre/post instruments: Group Assessment of Logical Thinking (GALT) measured logic ability, Purdue Visualizations of Rotations (ROT) Test measured spatial skills, and the California ...
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The Nature of Intermediates Produced Through Ligand-Substitution Reactions of Octahedral Metal Carbonyls

The Nature of Intermediates Produced Through Ligand-Substitution Reactions of Octahedral Metal Carbonyls

Date: May 1986
Creator: Mansour, Saber E. (Saber El-Sayed)
Description: Pulsed laser time-resolved ligand-substitution photochemistry for (DTO)W(CO)4, (DTN)W(CO)4, and (NP)Mo(CO)4 (DTO = 2,2,7,7-tetramethyl-3,6-diathiaoctane; DTN = 2,2,8,8- tetramethyl-3,7-diathianonane; NP = l-diethylamino-2- diphenylphosphinoethane) proceeds via initial fission of the W-S and Mo-P bonds, affording Cs and C4v five-coordinate intermediates for DTN and NP but largely Cs for DTO. The rates of reaction of these intermediates, via chelate ring closure and competitive bimolecular interaction with Lewis bases (= L, alkylphosphines and alkyl phosphites) for the Cs intermediates and via bimolecular interaction of L with the C4v intermediates, together with activation parameters for these processes have been determined. The rates of interactions at the Cs intermediates are significantly faster than at the C4v intermediates.
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Selective Lipid Absorption

Selective Lipid Absorption

Date: January 1960
Creator: Marcia, John Albion
Description: An experiment was designed to study in the same animal any preferential absorption of a free fatty acid in the presence of a triglyceride of the same fatty acid. Rats were administered a mixture of free fatty acid and its triglyceride labeled with carbon-13 and carbon-14 respectively. Each isotope in the fed lipid and in the lipid recovered from the gastrointestinal tract was measured. The isotope effect, if any, was studied by administering a mixture of palmitic acid-1-C13 and palmitic acid-1-C14.
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